1. Field of the Invention
The present invention relates to a stencil printer and more particularly to control to be executed over a stencil printer when the power supply of the printer is turned on after turn-off.
2. Description of the Background Art
A thermosensitive, digital stencil printer using a laminate type of stencil is conventional. The laminate type of stencil is made up of a thermoplastic resin film and a porous base adhered to the resin film and implemented by Japanese paper fibers or synthetic fibers or a mixture thereof. The stencil printer includes a rotatable print drum consisting of a hollow, porous support and a plurality of mesh screens wrapped around the support in a laminate and formed of resin or metal. After the resin film of the stencil has been perforated or cut by, e.g., a thermal head, the stencil is wrapped around the print drum. While ink is fed from ink feeding means arranged inside the print drum, press roller or similar pressing means continuously presses a sheet fed from sheet feeding means against the perforated stencil (master hereinafter) wrapped around the print drum. As a result, the ink is transferred to the sheet via the porous portion of the print drum and the perforations of the master, printing an image on the sheet.
Today, the stencil printer described above can automatically, continuously execute a sequence of steps of image reading, master discharging, master making, master wrapping, printing and so forth and implements high image accuracy and low printing cost. With these advantages, the stencil printer is replacing a copier when it comes to users of the kind usually desiring about ten or more prints.
The conventional stencil printer immediately stops operating when the main switch of the printer is accidentally turned off by hand or due to a power failure or the operation of a circuit breaker. Assume that the main power supply is turned off when the perforation of the master is under way, and again turned on. Then, in a first type conventional stencil printer configured to wrap the master around the print drum while perforating the master, the stencil is cut on the turn-on of the main power supply. On the other hand, in a second type of conventional stencil printer configured to stock the perforated portion of the stencil corresponding to a single master, the master is cut away on the turn-on of the main power supply and then wrapped around the print drum.
However, the problem with the first type of stencil printer stated above is that the cut piece of the master must be removed by hand before the turn-on of the power supply because the master has been cut without regard to its length, resulting in troublesome work. On the other hand, in the second type of stencil printer, because the master with a short length is left on the print drum, it is likely that the porous portion of the print drum is not entirely covered with the master when the main power supply is again turned on. This brings about a problem that the trailing edge of a sheet is smeared with ink, a problem that ink deposits on the press roller, and a problem that ink flown away via the porous portion of the print drum smears the inside of the printer.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication No. 7-257002, 7-257003 and 9-71029.
It is an object of the present invention to provide a stencil printer capable of resuming, when a power supply thereof is turn on after turn-off occurred during master making operation, the master making operation while promoting efficient work and protecting itself and a sheet from smears.